Next Article in Journal
CPP-Assisted Intracellular Drug Delivery, What Is Next?
Next Article in Special Issue
Hydrogen Bonding Interaction between Atmospheric Gaseous Amides and Methanol
Previous Article in Journal
Effect of Post-Translational Amidation on Islet Amyloid Polypeptide Conformational Ensemble: Implications for Its Aggregation Early Steps
Previous Article in Special Issue
Linear Response Function of Bond-Order
Article Menu
Issue 11 (November) cover image

Export Article

Open AccessArticle
Int. J. Mol. Sci. 2016, 17(11), 1893; doi:10.3390/ijms17111893

The Thermodynamic and Kinetic Properties of 2-Hydroxypyridine/2-Pyridone Tautomerization: A Theoretical and Computational Revisit

1
Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia
2
Chemistry Department, Faculty of Science, University of Khartoum, P.O. Box 321, Khartoum 11111, Sudan
3
Chemistry Department, Faculty of Science, Cairo University, Cairo 11258, Egypt
*
Author to whom correspondence should be addressed.
Academic Editor: Mihai V. Putz
Received: 26 August 2016 / Revised: 30 October 2016 / Accepted: 31 October 2016 / Published: 14 November 2016
(This article belongs to the Special Issue Chemical Bond and Bonding 2016)
View Full-Text   |   Download PDF [1641 KB, uploaded 14 November 2016]   |  

Abstract

The gas-phase thermal tautomerization reaction between 2-hydroxypyridine (2-HPY) and 2-pyridone (2-PY) was investigated by applying 6-311++G** and aug-cc-pvdz basis sets incorporated into some density functional theory (DFT) and coupled cluster with singles and doubles (CCSD) methods. The geometrical structures, dipole moments, HOMO-LUMO energy gaps, total hyperpolarizability, kinetics and thermodynamics functions were monitored against the effects of the corrections imposed on these functionals. The small experimental energy difference between the two tautomers of 3.23 kJ/mol; was a real test of the accuracy of the applied levels of theory. M062X and CCSD methods predicted the preference of 2-HPY over 2-PY by 5–9 kJ/mol; while B3LYP functional favoured 2-PY by 1–3 kJ/mol. The CAM-B3LYP and ωB97XD functionals yielded mixed results depending on the basis set used. The source of preference of 2-HPY is the minimal steric hindrance and electrostatic repulsion that subdued the huge hyperconjugation in 2-PY. A 1,3-proton shift intramolecular gas-phase tautomerization yielded a high average activation of 137.152 kJ/mol; while the intermolecular mixed dimer interconversion gave an average barrier height of 30.844 kJ/mol. These findings are boosted by a natural bond orbital (NBO) technique. The low total hyperpolarizabilities of both tautomers mark out their poor nonlinear optical (NLO) behaviour. The enhancement of the total hyperpolarizability of 2-HPY over that of 2-PY is interpreted by the bond length alternation. View Full-Text
Keywords: 2-hydroxypyridine; 2-pyridone; tautomerization; NBO; NLO 2-hydroxypyridine; 2-pyridone; tautomerization; NBO; NLO
Figures

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Supplementary material

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Hejazi, S.A.; Osman, O.I.; Alyoubi, A.O.; Aziz, S.G.; Hilal, R.H. The Thermodynamic and Kinetic Properties of 2-Hydroxypyridine/2-Pyridone Tautomerization: A Theoretical and Computational Revisit. Int. J. Mol. Sci. 2016, 17, 1893.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Int. J. Mol. Sci. EISSN 1422-0067 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top